• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.1769-1777
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• 2018

This paper proposes a method for optimal placement of Phasor Measurement Units (PMUs) considering system configuration and its attributes during the planning phase of PMU deployment. Each bus of the system is assessed on four diverse attributes; namely, redundancy of measurements, rotor angle and frequency monitoring of generator buses, reactive power deficiency, and maximum loading limit under transmission line outage contingency, and a consolidated 'degree of criticality' is determined using Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). The major contribution of the proposed work is the development of modified objective function which incorporates values of the degree of criticality of buses. The problem is formulated as maximization of the aggregate degree of criticality of the system. The resultant PMU configuration extends complete observability of the system and majority of the PMUs are located on critical buses. As budgetary restrictions on utilities may not allow installation PMUs even at optimal locations in a single phase, multi-horizon deployment of PMUs is also addressed. The proposed approach is tested on IEEE 14-bus, IEEE 30-bus, New England (NE) 39-bus, IEEE 57-bus and IEEE 118-bus systems and compared with some existing methods.

• Bulletin of the Korean Chemical Society
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• 제22권8호
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• pp.872-876
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• 2001

Topological changes caused by the alkaline and enzymatic attacks of solution-grown, chain-folded lamellar crystals (SGCs) of poly[(R)-3-hydroxybutyrate] P(3HB) have been studied in order to investigate the chain-folding structure in P(3HB) crystal regions. NaOH and an extracellular PHB depolymerase purified from Alcaligenes faecalis T1 were used for alkaline and enzymatic hydrolysis, respectively. The measurements were performed on crystals attached to a substrate which is inactive to degradation mediums. Both alkaline and enzymatic attacks lead to a breakup of the lamellar crystals along the crystallographic b-axis during initial erosion. Since hydrolysis preferentially occurs in amorphous regions, this morphological result reflects relatively loosely packed chains in core parts of lamellar crystals. Additionally, it was supported by the ridge formation along the b-axis in the lamellar crystals after thermal treatment at a low temperature because of the thermally sensitive nature of the loosely packed chains in lamellar crystals. However, the alkaline hydrolysis accompanied the chain erosions or scissions in quasi-regular folded lamellar surfaces due to smaller size of alkaline ions in comparison to the enzyme, resulting in the decrease of molecular weight.

• 대한전자공학회논문지SD
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• 제46권4호
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• pp.28-36
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• 2009

Sequence-Pair(SP) 모델은 모듈간의 위상 관계를 표현하는 방법으로써, 일반적으로 SP 모델에 기반한 플로어플래너(floorplanner)는 Simulated-Annealing(SA) 알고리즘을 통해 해를 탐색한다. 다양한 논문에서 SP와 SA 기반 배치 알고리즘의 성능 향상을 위해 SP의 평가 함수의 개선, SA의 스케줄링 기법 향상과 변형 함수의 개선 등을 모색하였다. 제안 기법은 기존의 SA 프레임웍을 수정한 2단계 SA 알고리즘으로써, 전 단계에선 SP로부터 구한 플로어플랜에 압축기법을 적용하여 모듈 사이에 존재하는 빈 공간을 가능한 최소화시켰다. 압축기법이 적용된 플로어플랜으로터 SP를 얻고, 이를 변환함으로써 해 공간을 탐색해 간다. 해가 기준 값에 수렴되었다고 판단되면 전 단계의 SA 기반 검색을 중단하고 압축기법을 사용하지 않은 기존의 SA 프레임웍을 이용하여 최적 해를 계속 탐색해 간다. MCNC 벤치마크 회로를 이용한 실험을 통해 제안 기법이 SA의 해 탐색 과정에 끼치는 효과를 보이며, 제안 기법을 통해 얻은 결과가 기존의 SA 기반 알고리즘으로 구한 결과보다 우수함을 보인다.

• 한국CDE학회논문집
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• 제10권6호
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• pp.444-454
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• 2005

Recently, the requirements of multi-resolution models of a solid model, which represent an object at multiple levels of feature detail, are increasing for engineering tasks such as analysis, network-based collaborative design, and virtual prototyping and manufacturing. The research on this area has focused on several topics: topological frameworks for representing multi-resolution solid models, criteria for the level of detail (LOD), and generation of valid models after rearrangement of features. As a solution to the feature rearrangement problem, the new concept of the effective zone of a feature is introduced in the former part of the paper. In this paper, we propose a feature-based non-manifold modeling system to provide multi-resolution models of a feature-based solid or non-manifold model on the basis of the effective feature zones. To facilitate the implementation, we introduce the class of the multi-resolution feature whose attributes contain all necessary information to build a multi-resolution solid model and extract LOD models from it. In addition, two methods are introduced to accelerate the extraction of LOD models from the multi-resolution modeling database: the one is using an NMT model, known as a merged set, to represent multi-resolution models, and the other is storing differences between adjacent LOD models to accelerate the transition to the other LOD. We also suggest the volume of the feature, regardless of feature type, as a criterion for the LOD. This criterion can be used in a wide range of applications, since there is no distinction between additive and subtractive features unlike the previous method.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2011년도 춘계학술발표대회
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• pp.346-349
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• 2011

In this paper, we design a perceptually invisible dot pattern layout and its recognition scheme, and we apply the recognition scheme into a smart self learning aid for interactive learning aid. To increase maximum information capacity and also increase robustness to the noises, we design a ECC (error correcting code) based dot pattern with directional vector indicator. To make a smart self-learning aid, we embed the micro dot pattern (20 information bit + 15 ECC bits + 9 layout information bit) using K ink (CMYK) and extract the dot pattern using IR (infrared) LED and IR filter based camera, which is embedded in the smart pen. The reason we use K ink is that K ink is a carbon based ink in nature, and carbon is easily recognized with IR even without light. After acquiring IR camera images for the dot patterns, we perform layout adjustment using the 9 layout information bit, and extract 20 information bits from 35 data bits which is composed of 20 information bits and 15 ECC bits. To embed and extract information bits, we use topology based dot pattern recognition scheme which is robust to geometric distortion which is very usual in camera based recognition scheme. Topology based pattern recognition traces next information bit symbols using topological distance measurement from the pivot information bit. We implemented and experimented with sample patterns, and it shows that we can achieve almost 99% recognition for our embedding patterns.